Amphiphilicity-Driven Small Alcohols Regulate the Flexibility of Pesticide-Loaded Microcapsules for Better Foliar Adhesion and Utilization

Core reinforcement strategy enhances the foliar stability and efficacy of electrostatic self-assembled microcapsules

BACKGROUND

At present, it is vital to develop a stable and efficient pesticide delivery system to optimize pesticide foliar utilization, which could improve control efficacy, enhance resistance to adverse climates, and prolong foliar retention. In this study, reaction monomers methylene diphenyl diisocyanate (MDI) and polycaprolactone diol (PCL) were used to synthesize a polymer network structure for loading the organic phase of pesticides in a micron-reactor, then the shell was formed by sodium lignosulfonate (SL) and didecyl dimethyl ammonium chloride (DDAC) through electrostatic self-assembly, resulting in self-assembled microcapsules and efficient pesticide loading, and the stability and efficacy were discussed.

RESULTS

Self-assembled microcapsules Pyr@MCs-C and Pyr@MCs-V with cores of different mechanical strength and morphological characteristics are realized by regulating the reaction ratio of MDI and PCL. Compared with conventional self-assembled microcapsule Pyr@MCs-S, Pyr@MCs-C and Pyr@MCs-V exhibit stable and unruptured morphology in dehydrated environment. Moreover, self-assembled microcapsules provide similar fungicidal activity as emulsifiable concentrate. Notably, the washout resistance property of Pyr@MCs-C and Pyr@MCs-V increased by 3.20 and 3.51 times, respectively, and ultraviolet (UV) resistances of the two microcapsules increased by 5.72 and 5.02 times, respectively, which promote the control efficiency and prolong the duration.

CONCLUSION

In summary, this system has simple preparation process and stable foliar performances, making it a promising precise pesticide delivery platform. © 2025 Society of Chemical Industry.

Polymer Capsules with Volatile Organic Compounds as Reference Materials for Controlled Emission

Encapsulation of volatile organic compounds (VOCs) that could evaporate at a defined rate is of immense interest for application in emission reference materials (ERMs). Polyurethane/polyurea microcapsules with various VOC active ingredients (limonene, pinene, and toluene) were successfully produced by interfacial polymerization with Shirasu porous glass membrane emulsification in a size range between 10 and 50 μm. The effect of surfactant, VOC, monomer(s) type, and ratio has a great effect on the formulation process and morphology of capsules. The type of VOC played a significant role in the encapsulation efficiency. Due to the difference in vapor pressure and VOC/water interfacial tension, the formulation for encapsulation was optimized for each individual VOC. Furthermore, to achieve effective stability of the large droplets/capsules, a combination of ionic and nonionic surfactants was used. Optical and scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were used to characterize the optimized microcapsules. The results showed that the obtained microcapsules exhibited a spherical shape and core-shell morphology and featured characteristic urethane-urea bonds. The amount of encapsulated VOC ranges between 54 and 7 wt %. The emission tests were performed with the help of the emission test chamber procedure (EN 16516). The limonene-loaded polyurethane/polyurea microcapsules show a change in emission rate of less than 10% within 14 days and can be considered as a potential candidate for use as an ERM.

pH-Responsive MOF Nanoparticles Equipped with Hydrophilic "Armor" Assist Fungicides in Controlling Peanut Southern Blight

The development of novel, safe, and efficient pest and disease control technologies for agricultural crops remains a pivotal area of research. In this study, by combining ZIF-8 and ZIF-90, a water-stable, pH-responsive bilayer MOF nanoparticle (NP) named Z8@Z90 was created, and tebuconazole (TEB) was added to form T@Z8@Z90, used for controlling peanut southern blight. The loading efficiency of TEB within the T@Z8@Z90 reached 26.15%, enabling rapid release in acidic environments triggered by oxalic acid (OA) secreted by Sclerotium rolfsii. In vitro experiments showed that T@Z8@Z90 can regulate the oxalic acid secretion of S. rolfsii and destroy its cell membrane structure. Additional experiments revealed that T@Z8@Z90 reduced sclerotial formation, decreased the total protein content of sclerotia, and influenced their sensitivity to pesticides, thereby mitigating the risk of reinfection by S. rolfsii. Notably, T@Z8@Z90 exhibited efficient translocation within peanut seedlings, being absorbed through the roots and transported to the leaves. At a concentration of 200 mg/L, T@Z8@Z90 exhibited high safety profiles for peanut seedling growth compared to the TEB suspension. Moreover, T@Z8@Z90 is safer for earthworms than TEB SC. Overall, this study offers valuable insights for the management of soil-borne diseases in agriculture and contributes to the advancement of sustainable agricultural practices.

Lignin microcapsules prepared on the basis of flexible skeleton with high foliar retention and UV shielding properties

Lignin-based microcapsules are extremely attractive for their biodegradability and photolysis resistance. However, the water-soluble all-lignin shells were unsatisfactory in terms of rainfall and foliar retention, and lacked the test of agricultural production practices. Herein, a novel microcapsule based on a flexible skeleton formed by interfacial polymerization and absorbed with lignin particles (LPMCs) was prepared in this study. Further analysis demonstrated that the shell was formed by cross-linking the two materials in layers and showed excellent flexibility and photolysis resistance. The pesticide loaded LPMCs showed about 98.68 % and 73.00 % improvement in scour resistance and photolysis resistance, respectively, as compared to the bare active ingredient. The foliar retention performance of LPMCs was tested in peanut plantations during the rainy season. LPMCs loaded with pyraclostrobin (Pyr) and tebuconazole (Teb) exhibited the best foliar disease control and optimum plant architecture, resulting in an increase in yield of about 5.36 %. LPMCs have a promising application prospect in the efficient pesticide utilization, by controlling its deformation, adhesion and release, an effective strategy for controlling diseases and managing plant growth was developed.

Multi-Stimuli-Responsive, Topology-Regulated, and Lignin-Based Nano/Microcapsules from Pickering Emulsion Templates for Bidirectional Delivery of Pesticides

The increasing demand for improving pesticide utilization efficiency has prompted the development of sustainable, targeted, and stimuli-responsive delivery systems. Herein, a multi-stimuli-responsive nano/microcapsule bidirectional delivery system loaded with pyraclostrobin (Pyr) is prepared through interfacial cross-linking from a lignin-based Pickering emulsion template. During this process, methacrylated alkali lignin nanoparticles (LNPs) are utilized as stabilizers for the tunable oil-water (O/W) Pickering emulsion. Subsequently, a thiol-ene radical reaction occurs with the acid-labile cross-linkers at the oil-water interface, leading to the formation of lignin nano/microcapsules (LNCs) with various topological shapes. Through the investigation of the polymerization process and the structure of LNC, it was found that the amphiphilicity-driven diffusion and distribution of cyclohexanone impact the topology of LNC. The obtained Pyr@LNC exhibits high encapsulation efficiency, tunable size, and excellent UV shielding to Pyr. Additionally, the flexible topology of the Pyr@LNC shell enhances the retention and adhesion of the foliar surface. Furthermore, Pyr@LNC exhibits pH/laccase-responsive targeting against Botrytis disease, enabling the intelligent release of Pyr. The in vivo fungicidal activity shows that efficacy of Pyr@LNC is 53% ± 2% at 14 days postspraying, whereas the effectiveness of Pyr suspension concentrate is only 29% ± 4%, and the acute toxicity of Pyr@LNC to zebrafish is reduced by more than 9-fold compared with that of Pyr technical. Moreover, confocal laser scanning microscopy shows that the LNCs can be bidirectionally translocated in plants. Therefore, the topology-regulated bidirectional delivery system LNC has great practical potential for sustainable agriculture.

Eucalyptol-loaded microcapsules combined with Cynanchum komarovii extracts provide long-term and low-risk management of Chinese wolfberry (Lycium barbarum L.)

Realizing eco-friendly, long-term, and low-risk aphid control on Lycium barbarum (medicinal cash crop) using a Cynanchum komarovii extracts and eucalyptus oil-loaded microcapsules (EOMCs) formulation compositions is viable. In this study, the aim is to optimize the composition of Cynanchum komarovii extracts and EOMCs formulation for effective control of aphids, the release of EOMCs was controlled by changing the cross-linking degree of the shell to match the aphid control characteristics of Cynanchum komarovii extracts. Four types of polyamines were used as cross-linking agents for the preparation of EOMCs by interfacial polymerization. The bioactivity, wettability, and field application efficacy of Cynanchum komarovii extracts and different EOMCs formulation compositions were evaluated. These EOMCs exhibited an encapsulation efficiency exceeding 85 %. The control efficiency of the formulation compositions of microcapsules with a moderate release rate and Cynanchum komarovii extracts on aphids remained at 62.86 %, while the control efficiency of the combination of microcapsules with the fastest and slowest rates with Cynanchum komarovii extracts was only 48.62 % and 57.11 %, respectively. The formulation compositions of Cynanchum komarovii extracts with all four types of EOMCs were found to be safe for Chinese wolfberry plants. Overall, by selecting appropriate polyamines during fabrication, the release rate can be effectively controlled to achieve sustainable and low-risk aphid control in Lycium barbarum through compounding with selected microcapsules.